JP2003158881A - High frequency conversion circuit - Google Patents

Abstract

(57) [Problem] To improve a power factor by making a waveform of an AC input current into a sine wave shape. SOLUTION: Two capacitors 5 are provided between AC input terminals 3 and 4 of a bridge rectifier circuit comprising diodes 7 to 10.
6 and a smoothing capacitor 1 is connected between the positive and negative electrodes on the DC output side of the rectifier circuit.
1 and switching element 12 for high frequency switching
And a switching arm in which a diode 14 is connected in anti-parallel, and a parallel connection circuit with a switching arm series circuit including a switching arm in which a switching element 13 and a diode 15 are also connected in anti-parallel. The reactor 33 is connected between the switching arm series circuit and the series connection point, and both ends of either switching arm are connected to the high frequency output terminals 20 and 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of constructing a conversion circuit for producing a high frequency alternating current from an alternating current power source of a commercial frequency by utilizing a resonance phenomenon, and more particularly to improving a waveform of an alternating input current to improve a power factor. The present invention relates to a high-frequency conversion circuit that produces high-frequency alternating current with high efficiency. Further, examples of application of the present invention include an induction heating device and a discharge lamp lighting device that directly use high frequency alternating current, and a direct current power supply device (switching power supply device) that indirectly uses high frequency alternating current.

[0002]

2. Description of the Related Art As a circuit configuration of this type, the circuit configuration shown in FIG. 14 is conventionally known as described in Japanese Patent Application Laid-Open No. 9-185997, "Lighting control device and lamp lighting device". Note that FIG. 14 is modified so that a part of the circuit configuration described in the above publication can be easily explained.

In this configuration, the alternating current of the alternating current power supply 1 is converted into direct current by the rectifying circuit composed of the diodes 7 to 10 and smoothed by the capacitor 11. Further, a capacitor series circuit composed of capacitors 18 and 19, an anti-parallel connection circuit composed of a switching element 12 and a diode 14 for high frequency switching, and a switching element 13.
And an anti-parallel connection circuit including a diode 15 and a switching arm series circuit including a series circuit, which are connected in parallel to the capacitor 11. Further, the primary winding of the transformer 28 is connected between the series connection point of the capacitor series circuit and the series connection point of the switching arm series circuit, and the discharge lamp 26 and the capacitor 27 are connected to the secondary winding thereof. There is.

In the above structure, the switching element 13
When the switching element 12 is turned on when is off,
Resonance between the capacitor 18 and the leakage inductance of the transformer 28 causes a resonance current to flow in the primary winding, and at the same time, the discharge lamp 2
A current also flows through 6. If the switching element 12 is turned off before this current is inverted, the diode 15 is turned on, and a resonance circuit is formed by the capacitor 19 and the leakage inductance of the primary winding of the transformer 28. At this time,
When the switching element 13 is turned on, a current flows through the switching element 13 due to the inversion of the resonance current.

When the switching element 13 is turned off in this state, the diode 14 is turned on, and a resonance circuit is formed by the capacitor 18 and the leakage inductance of the transformer 28. At this time, if the switching element 12 is turned on, the switching element 12 is turned on by the inversion of the resonance current.
Current flows through. By repeating the above operation at a high frequency, a high frequency alternating current flows through the transformer 28, and at the same time, a high frequency alternating current also flows through the discharge lamp 26. Here, the condenser 27 is for preheating the filament.

[0006]

As described above, conventionally, a rectifier circuit is used to generate direct current from the alternating current power supply 1, and then an inverter having switching elements 12 and 13 is used to generate high frequency alternating current. In this circuit configuration, since the smoothing capacitor 11 is used in the DC portion of the rectifier circuit, the AC input current has a waveform having a large peak value including many harmonics. Therefore, there is a problem that the power factor on the input side is low, the power supply voltage waveform is distorted, and the like, which adversely affects other devices connected to the AC power supply. Therefore, the present invention is intended to provide a high frequency conversion circuit in which the waveform of an AC input current is made sinusoidal to improve the power factor.

[0007]

In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that a capacitor series circuit composed of two capacitors is connected between AC input terminals of a diode bridge rectification circuit, and the rectification circuit is connected. A parallel connection circuit of a smoothing capacitor and a switching arm series circuit composed of two switching arms in which switching elements and diodes for high frequency switching are connected in antiparallel is connected between the positive and negative electrodes on the DC output side of A reactor is connected between a series connection point of a capacitor series circuit and a series connection point of the switching arm series circuit, and both ends of any one of the switching arms are connected to a high frequency output terminal.

According to a second aspect of the present invention, a first capacitor series circuit composed of two capacitors is connected between the AC input terminals of the diode bridge rectifier circuit, and the positive and negative electrodes on the DC output side of the rectifier circuit are connected. In between, a smoothing capacitor,
A parallel connection circuit of a switching arm series circuit composed of two switching arms in which switching elements and diodes for high frequency switching are connected in anti-parallel and a second capacitor series circuit composed of two capacitors is connected to form a first capacitor. A reactor is connected between a series connection point of a series circuit and a series connection point of the switching arm series circuit, and a series connection point of the switching arm series circuit and a series connection point of a second capacitor series circuit are connected to a high frequency output terminal. Connected to.

According to a third aspect of the present invention, in the high-frequency conversion circuit according to the first or second aspect, by connecting a capacitor in parallel with one or both switching arms, soft switching is performed when the switching element is off. It is possible to operate.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show an embodiment of the invention described in claim 1, FIG. 1 is a first embodiment in which the present invention is applied to an induction heating device, and FIG. 2 is a second embodiment in which a discharge lamp lighting device is applied. FIG. 3 shows a third embodiment applied to a DC power supply device.

First, in the first embodiment of FIG. 1, capacitors 5 and 6 are provided between the AC input terminals 3 and 4 of the diode bridge rectifying circuit composed of the diodes 7 to 10.
Is connected to the first capacitor series circuit.
A capacitor 11 is connected between the positive electrode and the negative electrode on the DC output side of the rectifier circuit, and a switching element 12 and a diode 14 for high frequency switching are connected in antiparallel to both ends of the capacitor 11. Is connected to a switching arm series circuit including a switching arm and a second switching arm in which a switching element 13 and a diode 15 that are high-frequency switched are connected in antiparallel. A reactor 33 is connected between a connection point of the first capacitor series circuit and a series connection point of the first and second switching arms, and both ends of the second switching arm have high frequency output terminals 20, 21. Has become.

A series circuit of an AC power supply 1 and a reactor 2 is connected between the AC input terminals 3 and 4, and a heating coil 23 and a capacitor 2 are connected between the high frequency output terminals 20 and 21.
A heating load circuit including a series circuit of two parallel circuits and a capacitor 24 is connected.

In the above structure, the switching element 1
When the capacitors 2 and 13 are off, the capacitor 11 is charged to the peak value of the voltage of the AC power supply 1. When the switching element 12 is turned on while the switching element 13 is off, a current flows in a path that passes through the parallel circuit of the heating coil 23 and the capacitor 22 and the capacitor 24. At this time,
When the switching element 12 is turned off, the heating coil 23
Current flows in a direction to discharge the capacitor 22, and gradually decreases the voltage of the capacitor 22. Along with this, the diode 15 becomes conductive, and a current flows through a path that passes through the parallel circuit of the heating coil 23 and the capacitor 22, the capacitor 24, and the diode 15.

At this time, the voltage across the switching element 13 gradually rises, and the soft switching operation is performed. next,
When the switching element 13 is turned on, the current is inverted due to the resonance phenomenon, and the current flows in a path passing through the parallel circuit of the heating coil 23 and the capacitor 22 → the switching element 13 → the capacitor 24.

When the switching element 13 is turned off, the current of the heating coil 23 gradually increases the voltage of the capacitor 22, and the current path is a parallel circuit of the heating coil 23 and the capacitor 22 → diode 14 → capacitor 11
→ The path goes through the capacitor 24. At this time, since the voltage across the switching element 13 gradually rises, the soft switching operation is performed. Next, when the switching element 12 is turned on, the current is inverted due to the resonance phenomenon, and a path is formed through the capacitor 11, the switching element 12, the parallel circuit of the heating coil 23 and the capacitor 22, and the capacitor 24. By repeating such operation at high frequency,
A high frequency alternating current flows through the heating coil 23.

On the other hand, in the reactor 33, when the switching element 12 is on, the current increases along the path passing through the capacitor 5 → diode 7 → switching element 12, turning off the switching element 12 and switching element 1
When 3 is turned on, the current of the reactor 33 is: capacitor 5 → diode 7 → capacitor 11 → diode 15
The path becomes a path that passes through and decreases, and then the path that passes through the capacitor 6, the reactor 33, the switching element 13, and the diode 10 increases negatively.

Next, when the switching element 13 is turned off and the switching element 12 is turned on, the current of the reactor 33 changes from the diode 14 to the capacitor 11 to the diode 10.
→ It becomes the path of the capacitor 6. By repeating such an operation at high frequency, the voltage of the capacitor 11 becomes higher than the power supply voltage due to the boosting operation. In addition, reactor 2
The power supply current flowing through the sine wave has a sinusoidal shape by appropriately selecting the value of the reactor 33, and a high power factor can be obtained.

Here, FIG. 1 shows an example in which a series circuit of the AC power supply 1 and the reactor 2 is connected to the AC input terminals 3 and 4, but when the reactor is substituted by the wiring inductance, or when the reactor and the capacitor are used. It goes without saying that there are various possibilities such as when using an AC filter.

Next, FIG. 2 shows a second embodiment of the present invention applied to a discharge lamp lighting device using a discharge lamp as a load. Figure 1
The difference is with the circuit components connected to the high frequency output terminals 20 and 21. The high frequency output terminals 20 and 21 are provided with a parallel circuit of a reactor 25 and a capacitor 22,
A series circuit of a discharge lamp 26 in which a preheating capacitor 27 is connected to the filament and a capacitor 24 is connected. The reactor 25 is connected to the heating coil 23 in FIG.
If the discharge lamp 26 is considered as a load resistance, its operation is similar to that of FIG.

FIG. 3 shows a third embodiment of the present invention applied to a DC power supply device (switching power supply device). Figure 1,
The difference from FIG. 2 is the circuit components connected to the high frequency output terminals 20 and 21. High frequency output terminals 20, 21
A parallel circuit of the reactor 25 and the capacitor 22, and a series circuit of the primary winding of the transformer 28 and the capacitor 24 are connected to the. The anodes of diodes 29 and 30 are connected to both ends of the secondary winding of the transformer 28, and the cathodes of these diodes are connected to each other. A parallel circuit of a capacitor 31 and a load 32 is connected between these cathodes and the center tap of the transformer 28. Here, the reactor 25 is connected to the heating coil 2 of FIG.
3. If the circuit components after the transformer 28 are considered as load resistances, the operation is the same as in FIGS. 1 and 2.

Next, FIGS. 4 to 6 show claims 1 and 3.
4 is a fourth embodiment in which the present invention is applied to an induction heating device, FIG. 5 is a fifth embodiment in which a discharge lamp lighting device is applied, and FIG. 6 is a DC power supply device. It is the sixth embodiment.

First, the difference between FIG. 1 and FIG.
In the embodiment, there is no capacitor connected in parallel with the heating coil 23, and the switching element 12 and the diode 1 are not provided.
4 is that the capacitor 16 is connected in parallel to the anti-parallel circuit with respect to 4 and the capacitor 17 is connected in parallel with the anti-parallel connection circuit with the switching element 13 and the diode 15. The operation difference from the first embodiment in FIG. 1 is that the capacitor 16 is charged when the switching element 12 is turned off, and the capacitor 1 is turned on when the switching element 13 is turned off.
Since 7 is charged, the voltage gradually increases, and soft switching operation is performed to reduce switching loss. Other operations are the same as those in the first embodiment.

Similarly for the fifth embodiment of FIG. 5 and the sixth embodiment of FIG. 6, capacitors connected in parallel to the reactor 25 in the second embodiment of FIG. 2 and the third embodiment of FIG. 3, respectively. The difference is that the parallel capacitors 16 and 17 are additionally provided. Regarding the operation of these embodiments, the capacitor 16 is charged when the switching element 12 is turned off, and the capacitor 17 is charged when the switching element 13 is turned off, so that the voltage gradually increases and the soft switching operation is performed. The others are the same as those in the second and third embodiments.

In the embodiments shown in FIGS. 4 to 6, a capacitor may be connected in parallel to either one of the switching elements 12 and 13.

Next, FIG. 7 corresponds to another embodiment of the invention described in claim 1 and is a seventh embodiment applied to an induction heating device. The difference from the first embodiment of FIG. 1 is that
The high frequency output terminals 20 and 21 are connected to both ends of the switching element 13 in FIG. 1, whereas they are connected to both ends of the switching element 12 in FIG. 7. The operation is similar to that of FIG. 1 by reversing the on / off operation of the switching elements 12 and 13. The concept of changing the connection locations of the high-frequency output terminals 20 and 21 to reverse the on / off operation of the switching elements 12 and 13 is also applied to the second to sixth embodiments of FIGS. 2 to 6. It is possible.

8 to 10 show an embodiment of the invention described in claim 2, FIG. 8 is an eighth embodiment in which the present invention is applied to an induction heating device, and FIG. 9 is applied to a discharge lamp lighting device. Second Embodiment, FIG. 10 is a tenth embodiment applied to a DC power supply device.

The difference from the first to third embodiments of FIGS. 1 to 3 is that a second capacitor series circuit composed of capacitors 18 and 19 is connected in parallel with the switching arm series circuit, and a high frequency output terminal 20, 21 is the point connected to the series connection point of the switching arm series circuit and the series connection point of the second capacitor series circuit, respectively. In addition,
In the present embodiment, the series circuit of the capacitors 5 and 6 connected to the AC input terminals 3 and 4 is referred to as a first capacitor series circuit for convenience.

In FIG. 8, when the switching element 12 is turned on while the switching element 13 is off, a current flows in the route of capacitor 18 → switching element 12 → parallel circuit of heating coil 23 and capacitor 22 → capacitor 24. When the switching element 12 is turned off, the voltage of the capacitor 22 is discharged by the current of the heating coil 23 and gradually decreases, and then the diode 15 becomes conductive,
A parallel circuit of the heating coil 23 and the capacitor 22 → capacitor 24 → capacitor 19 → current of the path of the diode 15 is obtained. At this time, since the voltage across the switching element 12 gradually rises, the soft switching operation is performed.

When the switching element 13 is turned on, the current is inverted due to the resonance phenomenon and a path is formed through the capacitor 19 → the capacitor 24 → the parallel circuit of the heating coil 23 and the capacitor 22 → the switching element 13. Here, when the switching element 13 is turned off, the voltage of the capacitor 22 is charged by the current of the heating coil 23 and gradually rises, and then the diode 14 becomes conductive and the capacitor 18 →
The current flows in the path of the parallel circuit of the condenser 24 → the heating coil 23 and the condenser 22. At this time, since the voltage across the switching element 13 gradually rises, the soft switching operation is performed. When the switching element 12 is turned on, the current is inverted due to the resonance phenomenon, and the capacitor 1
The route is 8 → switching element 12 → parallel circuit of heating coil 23 and capacitor 22 → capacitor 24.

By repeating such an operation at a high frequency, a high frequency alternating current flows through the heating coil 23.
On the other hand, the current of the reactor 33 increases when the alternating current power supply 1 has a positive polarity and the switching element 12 is on, and the current increases in a path passing through the capacitor 5, the diode 7, and the switching element 12, and the switching element 12 is turned off. When the switching element 13 is turned on, the current of the reactor 33 changes from the capacitor 5 to the diode 7 to the capacitor 11
→ It decreases on the path passing through the diode 15, and then increases negatively on the path passing through the capacitor 6 → reactor 33 → switching element 13 → diode 10.

Next, when the switching element 13 is turned off and the switching element 12 is turned on, the current of the reactor 33 changes from the diode 14 to the capacitor 11 to the diode 10.
→ It becomes the path of the capacitor 6.

When the AC power source 1 has a negative polarity and the switching element 12 is on, the capacitor 6 →
When the current increases in the path passing through the diode 9 → switching element 12, the switching element 12 is turned off and the switching element 13 is turned on, the current in the reactor 33 decreases in the path passing through the capacitor 5 → diode 7 → capacitor 11 → diode 15. Then, it increases negatively on the path that passes through the capacitor 5, the reactor 33, the switching element 13, and the diode 8. Next, when the switching element 13 is turned off and the switching element 12 is turned on, the current of the reactor 33 becomes a path of the diode 14 → capacitor 11 → diode 10 → capacitor 6. By repeating such an operation at a high frequency, the voltage of the capacitor 11 becomes higher than the power supply voltage due to the boosting operation.

Further, the power supply current flowing through the reactor 2 becomes sinusoidal by appropriately selecting the value of the reactor 33, and a high power factor can be obtained. Here, an example is shown in which a series circuit of the AC power supply 1 and the reactor 2 is connected to the AC input terminals 3 and 4, but when the reactor is substituted by the wiring inductance, or when the AC filter including the reactor and the capacitor is used, etc. Needless to say, there are various possibilities.

FIG. 9 shows a ninth embodiment of the present invention applied to a discharge lamp lighting device using a discharge lamp as a load. The difference from FIG. 8 is the circuit components connected to the high frequency output terminals 20 and 21. That is, the high frequency output terminals 20 and 2
1, a parallel circuit of a reactor 25 and a capacitor 22, a discharge lamp 26 in which a preheating capacitor 27 is connected to a filament, and a series circuit of a capacitor 24 are connected. If the reactor 25 is considered as the heating coil 23 in FIG. 8 and the discharge lamp 26 is considered as the load resistance, the operation is similar to that in FIG.

FIG. 10 shows a tenth embodiment of the present invention applied to a DC power supply device. The difference from FIG. 8 and FIG. 9 is the difference in the circuit components connected to the high frequency output terminals 20 and 21. The high frequency output terminals 20 and 21 are connected to a parallel circuit of a reactor 25 and a capacitor 22, and a series circuit of a primary winding of a transformer 28 and a capacitor 24. The diode 2 is connected across the secondary winding of the transformer 28.
The anodes of 9 and 30 are connected to each other, and these cathodes are connected to each other. In addition, a capacitor 3 is provided between these cathodes and the center tap of the transformer 28.
The parallel circuit of 1 and the load 32 is connected. here,
If the reactor 25 is considered to be the heating coil 23 of FIG. 1 and the circuit components after the transformer 28 are load resistances, the operation thereof is the same as that of FIGS. 1 and 2.

11 to 13 show claims 2 and 3.
11 is an embodiment of the invention described in FIG. 11, FIG. 11 is an eleventh embodiment of the invention applied to an induction heating device, FIG. 12 is a twelfth embodiment of the invention applied to a discharge lamp lighting device, and FIG.
Is a thirteenth embodiment of the present invention applied to a DC power supply device.

The difference between FIG. 8 and the eleventh embodiment of FIG. 11 is that in FIG. 11, there is no capacitor connected in parallel to the heating coil 23, and the switching element 12 and the diode 1
4 is that the capacitor 16 is connected in parallel with the anti-parallel connection circuit of No. 4 and the capacitor 17 is connected in parallel with the anti-parallel connection circuit of the switching element 13 and the diode 15. The difference in operation is that when the switching element 12 is turned off, the capacitor 16 is charged, and when the switching element 13 is turned off, the capacitor 17 is charged and the voltage gradually increases, so that the soft switching operation is performed.
Other operations are the same as those in FIG.

12th Embodiment of FIG. 12, 13th Embodiment of FIG.
Similarly for the embodiment, the ninth embodiment of FIG.
There is no capacitor connected in parallel to the reactor 25 as compared with the tenth embodiment of FIG.
The difference is that 6 and 17 are added. Regarding the operation of these embodiments, the capacitor 16 is charged when the switching element 12 is turned off, and the capacitor 17 is charged when the switching element 13 is turned off, so that the voltage gradually increases and the soft switching operation is performed. The other points are the same as those in the ninth and tenth embodiments.

In the embodiments of FIGS. 11 to 13, a capacitor may be connected in parallel to either one of the switching elements 12 and 13.

[0040]

As described above, in the present invention, the AC power supply voltage is divided into two by the capacitor series circuit, and the reactor is connected between the series connection point of the capacitor series circuit and the series connection point of the switching arm series circuit. Therefore, the boosting operation charges the smoothing capacitor through the reactor, and the current from the AC power supply can be made sinusoidal to have a high power factor. As a result, the problem of distorting the AC power supply voltage is eliminated, and the adverse effect on other devices can be eliminated.

[Brief description of drawings]

1 is a circuit diagram showing a first embodiment of the present invention based on claim 1. FIG.

2 is a circuit diagram showing a second embodiment of the present invention based on claim 1. FIG.

FIG. 3 is a circuit diagram showing a third embodiment of the present invention based on claim 1.

FIG. 4 is a circuit diagram showing a fourth embodiment of the present invention based on claims 1 and 3.

FIG. 5 is a circuit diagram showing a fifth embodiment of the present invention based on claims 1 and 3.

FIG. 6 is a circuit diagram showing a sixth embodiment of the present invention based on claims 1 and 3.

FIG. 7 is a circuit diagram showing a seventh embodiment of the present invention based on claim 1.

FIG. 8 is a circuit diagram showing an eighth embodiment of the present invention based on claim 2.

FIG. 9 is a circuit diagram showing a ninth embodiment of the present invention based on claim 2.

FIG. 10 is a circuit diagram showing a tenth embodiment of the present invention based on claim 2.

FIG. 11 is a circuit diagram showing an eleventh embodiment of the present invention based on claims 2 and 3.

FIG. 12 is a circuit diagram showing a twelfth embodiment of the present invention based on claims 2 and 3.

FIG. 13 is a circuit diagram showing a thirteenth embodiment of the present invention based on claims 2 and 3.

FIG. 14 is a circuit diagram showing a conventional technique.

[Explanation of symbols]

1 AC power supply 2, 25, 33 Reactor 3, 4 AC input terminals 5, 6, 11, 16 to 19, 22, 24, 27, 31
Capacitors 7 to 10, 14, 15, 29, 30 Diodes 12, 13 Switching elements 20, 21 High frequency output terminal 23 Heating coil 26 Discharge lamp 28 Transformer 32 Load

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3K072 AA02 AC02 AC11 BA03 BB01                       BB05 CA11 CA14 DB03 DD04                       GA01 GB12 GC04 HA05                 5H006 AA02 CA01 CA07 CB01 CC01                       CC02                 5H007 AA02 BB03 BB11 CA01 CB02                       CB05 CB09 CC01 CC03 EA08

Claims (3)

[Claims] 1. A diode series rectifier circuit, wherein a capacitor series circuit composed of two capacitors is connected between AC input terminals, and a smoothing capacitor and a high frequency switching are provided between a positive electrode and a negative electrode on the DC output side of the rectifier circuit. Connecting a parallel connection circuit with a switching arm series circuit composed of two switching arms in which switching elements and diodes are connected in anti-parallel, and connecting a series connection point of the capacitor series circuit and a series connection point of the switching arm series circuit. A high-frequency conversion circuit characterized in that a reactor is connected in between, and both ends of either switching arm are connected to a high-frequency output terminal. 2. A first capacitor series circuit composed of two capacitors is connected between AC input terminals of a diode bridge rectifier circuit, and a smoothing capacitor is provided between a positive electrode and a negative electrode on the DC output side of the rectifier circuit. Connecting a parallel connection circuit of a switching arm series circuit composed of two switching arms in which switching elements and diodes for high-frequency switching are connected in anti-parallel and a second capacitor series circuit composed of two capacitors, A reactor is connected between the series connection point of the capacitor series circuit and the series connection point of the switching arm series circuit, and the series connection point of the switching arm series circuit and the series connection point of the second capacitor series circuit are output at high frequencies. A high frequency conversion circuit characterized by being connected to a terminal. 3. The high frequency conversion circuit according to claim 1 or 2, wherein a capacitor is connected in parallel with one or both switching arms.